Combined guitar and synthesizer sound box



FIG. 1 is a top plan view of a combined guitar and synthesizer sound box, showing my new design;

FIG. 2 is a left side elevational view thereof;

FIG. 3 is a right side elevational view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a rear elevational view thereof, shown in the inverted position; and,

FIG. 6 is a front elevational view thereof. 

The ornamental design for a combined guitar and synthesizer sound box, as shown. 